A common mechanical objective is to mount a gear, wheel or pulley onto a shaft for rotation with the shaft. One known system for mounting a gear to a shaft (for example U.S. Pat. No. 6,000,875) employs two coaxial, nested sleeves that are threaded together. The inner sleeve has external asymmetrical threads to be fitted with outer sleeve having internal asymmetrical threads. The inner sleeve is slit so that threading the two together compresses and shrinks the inner sleeve. The outer sleeve has a slit and expands when threaded together. Thus the nested sleeves may be placed around a shaft and inside a gear so that when tightened, the sleeves engage and center the gear on the shaft, and hold it securely thereon for rotation therewith. See also U.S. Pat. Nos. 1,380,708, 3,957,381, 4,824,281, 4,848,953 and 5,067,846.
A drawback with some of these known mounting assemblies is the number of parts required between the shaft and the machine element, where accumulation of parts demands high tolerances and makes manufacturing difficult. Therefore, there is a need for a mounting assembly which is relatively simple to make for securely mounting a machine element to a shaft coaxially, for movement with the shaft, and which requires relatively few easily manufactured components.